Display devices for computer-driven and computer-assisted applications are in widespread use. Display devices now range is size from the very small, e.g., for handheld devices, to the very large, e.g., for large displays in conference halls and public spaces, both indoor and outdoor.
Challenges presented by very large display devices include the need for very high frequency signals to drive them. For example, a thin-film transistor (“TFT”) display device with a rectilinear configuration of 1,000×1,000 picture elements (“pixels,” an element of a visual image or picture), using a typical “row, column” addressing scheme, 256 intensity values and displaying 72 frames/second would require a driving signal frequency of (1,000 rows×256 intensity levels×72 frames/second)≈18.4 MHz, and 256 time intervals per frame are required to achieve 256 intensity levels. The 256 time intervals are required because one time interval is required to send either a 1 or a 0, the total of 256 of which bits represents the desired intensity for a given frame distributed time-wise through the frame to reduce artifacts.
Very high frequency signals can present design, operation and control issues. One such issue that becomes important at high frequencies is the effect of electromagnetic interference (“EMI”). This may be particularly important to consider in larger display devices because the required long electrical traces act as antennae. It would be beneficial to drive a given display with lower frequency signals and yet produce the same number of intensity levels, frames/second, etc.